<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>Document</title>
</head>
<body>
  <script>
  function sayHello() {//命名规范，括号后面有个空格
      console.log("HeloWold!")
      console.log("cyh")
      console.log("How are you!")
  }
    sayHello()//调用函数，只声明不调用，是不会执行的
  
  </script>
</body>
</html>